1. Field of the Invention
The subject matter of this invention is an electrical connector and a contact terminals used in that connector. The terminals are stamped and formed pin and socket terminals having defined contact points and lanceless contact retention sections. The connector housings are multiposition soft shell housings with keyed engagement.
2. Description of the Prior Art
Stamped and formed pin and socket electrical contact terminals mounted in multiposition soft shell housings are widely used for connecting electrical harnesses in a wide variety of applications. These soft shell pin and socket connectors are used in electrical appliances, automobiles, computers as well as similar applications. These prior art connectors are generally inexpensive to manufacture and use conventional materials such as brass or phosphor bronze for the contact terminals and conventional plastics such as Nylon for the insulation housing.
The most common form of these connectors use lanced contact terminals on both the stamped and formed female sockets and male pins which are crimped to the end of an insulated wire from which the insulation has been removed at the end of the wire. These terminals can be attached to wires using automated connector application machines. These lanced contact terminals typically have a stabilization section for centrally positioning the terminals in a single terminal cavity in the housing. This stabilization section is generally cylindrical and are normally located next to the wire crimp section of the terminal near the rear of the terminal.
Lanced stamped and formed pin and socket terminals typically have one or more lances formed outwardly from the generally cylindrical profile of the terminals between the stabilization section and the contact section of the terminals. These lances, which are in the form of a cantilever beam with one end joined to the terminal, extend at an acute angle with the ends of the lances facing the rear of the terminal. These ends of these lances extend outwardly beyond the inner dimension of the housing cavities in which the pin or socket contact section resides. When the pin or socket terminal is inserted into a housing cavity from the rear, the lances are inwardly deflected. When a terminal is fully inserted into its cavity, the lances will be located in a larger section of the cavity and the lances can spring back essentially to their normal position. A shoulder will generally be formed at the intersection of a larger cavity portion, in which the contact pin or socket portion of the terminal normally resides and the smaller portion of the cavity in which the crimp and stabilization sections of the terminals normally are located. The lances engage this shoulder to prevent withdrawal or back out of the terminal. A larger section of the terminal adjacent the rear of the terminals normally prevents the terminal from being inserted further into the cavity. The engagement between the lances and the housing shoulder provides the primary reaction surface against which a force is applied when pin and socket connectors are mated. These lances also prevent removal of the terminals prior to mating is a force is applied to the wires to which the terminals are attached. Since these connectors are typically applied on a mass production basis, reliable retention of the contact terminals in the housing is a important part of providing a quality assembly.
Although these traditional lanced pin and socket connectors continue to satisfactorily a wide variety of applications, there are problems associated with lanced pin and socket terminals. Although the terminals are stamped from resilient metals, the protruding lances can be overstressed, in which case they will not return to their normal position when released. Since the lances are exposed prior to insertion into the housing, this type of damage to the lances will occasionally occur. Since these terminals are used in large quantities, this type of damage is difficult to detect. These terminals are also used in connectors having multiple cavities, and one damaged terminal can result in a rejection of a larger connection. For example, sixteen position connectors are common and the percentage of defective connectors will be sixteen times the percentage of defective contact terminals.
Another problem with traditional lanced pin and socket terminals arises which these connectors are used in applications in which terminals at applied to a plurality of wires in a wiring harness. This is a typical use of pin and socket terminals in automotive and other applications. The wiring harness is assembled prior to insertion of the pin and socket terminals into the connector housing. The exposed lances on these terminals can easily snag the wires in the harness causing the harness to become entangled. The harnesses must then be disentangled adding an otherwise unnecessary manufacturing rework operation and thus adding cost to the assembly of the product in which the pin and socket terminal is used.
One solution to the some of the problems faced with lanced pin and socket terminals and connectors is the use of lanceless pin and socket terminals. Conventional lanceless pin and socket terminals have a small diameter or necked down section of the terminal between the pin or socket contact portion of the terminals and the terminal stabilization section of the terminal adjacent the rear of the terminals. A resilient plastic latch can be molded in the housing cavity. This plastic latch exhibits a resilient cantilever configuration and protrudes into the housing cavity. The latch deflects out of the way when the terminal is inserted and returns to its normal position when the smaller necked down section of the terminal is positioned next to the latch. The plastic latch then engages a shoulder formed on the pin or socket terminal to prevent withdrawal of the terminal. These lanceless pin and socket connectors have also met with considerable success and they quite satisfactorily meet the requirements of many applications. There are however certain problems associated with lanceless pin a socket connectors. Since the plastic latches must be resilient, the choice of material for the connector housing will be limited by this requirement. Thus the connectors may not be as inexpensive as they might otherwise be or they may not be able to satisfactorily meet the requirements of applications used in more stringent environments. Perhaps more importantly the presence of the latches in the housing results in a more expensive molded plastic housing. Additional material is required and the molds have more elaborate core pins for forming the housing cavities and therefore become more expensive to make and more expensive to operate. Additional cost is added to the final product. These plastic latches also can limit the size of the pin and socket connector which can effectively use lanceless pin and socket terminals. Smaller center to center distances for the terminals ultimately become unattainable with a lanceless terminal.
In some cases the contact retention attainable with both traditional lanced and conventional lanceless pin and socket terminals is unsatisfactory for a specific applications. In these cases a secondary lock is typically employed. These secondary locks typically engage some portion of the connector housing to provide additional backup for the terminals. Some secondary locks engage both the connector housing and the contact terminals. For example a secondary lock can be attached to the rear of the connector housing and can have a surface overlapping the rear of the terminal to prevent withdrawal. Some secondary locks also engage the resilient plastic latches to hold them in engagement with the lanceless pin or socket terminals. One form of this type of secondary lock can be inserted from the front of the housing between the end of the plastic latch and an adjacent surface of the housing. Some secondary locks are in the form of separate pieces which can be attached to the connector after assembly. These secondary locks can be attached to the rear or to the front, and in some cases are inserted into the housing from the side to prevent contact withdrawal. However, secondary locks in the form of distinct pieces can be lost or improperly assembled, and in any event constitute a separate part which must be inventoried and a separate manufacturing operation which add cost to the final product. Some secondary locks can be integral parts of the connector house and are typically are joined to the housing by a flexible web. At least one prior art connector employs a secondary lock of this type located at the rear of the main housing body. In some applications even secondary locking is not alone sufficient. Some assurance that the terminal is properly seated is required. This terminal position assurance is sometimes provided by a secondary lock with cannot be properly seated unless the terminals are properly positioned.
One objection, sometimes expressed in regard to any of these pin and socket terminals and connectors is that the cylindrical barrel shaped configuration of the typical pin as socket contact section does not provide a defined repeatable contact point for terminal to terminal engagement. Some concern has been expressed about the integrity of the contact interface for conventional pin and socket terminals. Reliable contact insertion forces have similarly been questioned. One alternative to the pin and socket terminal which is sometimes employed is a flat blade and socket configuration in which cantilever contact arms are used in the socket. A precise contact interface can be achieved by the engagement of these cantilever contact arms with the flat blade. However, these conventional blade and receptacle terminals can be inserted into an insulative housing in only one orientation. Again this complicates assembly of the connector and adds cost to the product.
Proper orientation of mating connectors is also important so that the connectors can only be mated in one orientation, thus insuring that only corresponding lines will be mated in multiposition electrical connectors. One conventional approach to the problem is to use slightly different cross sectional shapes for the housing cavities and housing silos in mating connectors. Some silos and cavities may have a circular cross section while others could have a square cross section and still others could have rounded corners, sometime having a generally D-shaped cross section. These different cross sections must be sufficiently different so that the soft shell housings cannot be deformed when excessive mating force is applied. Although this approach is generally reliable, one problem is that this approach requires the use of multiple core pins in the molds for each different cavity. A common cross section would permit the use of common core pins and the manufacture of many different housings with different numbers of contacts would be less expensive.